We report experimental results for a simple bimatrix game between a manager and an auditor. We investigate whether the quality of audited financial statements improves if the relative proportion of perfectly honest auditors increases. We find that the quality of audited reports is higher if computerized auditors who always perform a high audit effort are present. This result is in direct contrast to the Nash prediction for our game. The Quantal Response Equilibrium, which explicitly takes into account boundedly rational behavior, supports our experimental data. Our main findings depend neither on framing nor the payoff matrix we use.

This paper investigates the driving forces behind informal sanctions in cooperation games and the extent to which theories of fairness and reciprocity capture these forces. We find that cooperators' punishment is almost exclusively targeted toward the defectors, but the latter also impose a considerable amount of spiteful punishment on the cooperators. However, spiteful punishment vanishes if the punishers can no longer affect the payoff differences between themselves and the punished individual, whereas the cooperators even increase the resources devoted to punishment in this case. Our data also discriminate between different fairness principles. Fairness theories that are based on the assumption that players compare their own payoff to the group's average or the group's total payoff cannot explain the fact that cooperators target their punishment at the defectors. Fairness theories that assume that players aim to minimize payoff inequalities cannot explain the fact that cooperators punish defectors even if payoff inequalities cannot be reduced. Therefore, retaliation, i.e., the desire to harm those who committed unfair acts, seems to be the most important motive behind fairness-driven informal sanctions. Copyright The Econometric Society 2005.

Neuroeconomic Foundations of Trust and Social Preferences: Initial Evidence by Ernst Fehr, Urs Fischbacher and Michael Kosfeld. Published in volume 95, issue 2, pages 346-351 of American Economic Review, May 2005